aboutsummaryrefslogtreecommitdiff
path: root/drivers/arm/pl011/aarch32/pl011_console.S
blob: 96da6f92b9f284a1362a5e2750d28cb477840dc8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
/*
 * Copyright (c) 2018, Arm Limited. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
#include <arch.h>
#include <asm_macros.S>
#include <console.h>
#include <pl011.h>

	.globl	console_init
	.globl	console_putc
	.globl	console_getc
	.globl	console_try_getc
	.globl	console_flush
	.globl	console_core_init
	.globl	console_core_putc
	.globl	console_core_getc
	.globl	console_core_flush

	/*
	 *  The console base is in the data section and not in .bss
	 *  even though it is zero-init. In particular, this allows
	 *  the console functions to start using this variable before
	 *  the runtime memory is initialized for images which do not
	 *  need to copy the .data section from ROM to RAM.
	 */
	.section .data.console_base
	.align 2
console_base: .word 0x0

	/* -----------------------------------------------
	 * int console_init(uintptr_t base_addr,
	 * unsigned int uart_clk, unsigned int baud_rate)
	 * Function to initialize the console without a
	 * C Runtime to print debug information. It saves
	 * the console base to the data section.
	 * In: r0 - Console base address
	 *     r1 - Uart clock in Hz
	 *     r2 - Baud rate
	 * Out: r0 - Return 1 on success, 0 on error.
	 * Clobber list : r1 - r3
	 * -----------------------------------------------
	 */
func console_init
	ldr	r3, =console_base
	str	r0, [r3]
	b	console_core_init
endfunc console_init

	/* -----------------------------------------------
	 * int console_core_init(uintptr_t base_addr,
	 * unsigned int uart_clk, unsigned int baud_rate)
	 * Function to initialize the console without a
	 * C Runtime to print debug information. This
	 * function will be accessed by console_init and
	 * crash reporting.
	 * In: r0 - Console base address
	 *     r1 - Uart clock in Hz
	 *     r2 - Baud rate
	 * Out: r0 - Return 1 on success, 0 on error.
	 * Clobber list : r1 - r3
	 * -----------------------------------------------
	 */
func console_core_init
	/* Check the input base address */
	cmp	r0, #0
	beq	core_init_fail
	/* Check baud rate and uart clock for sanity */
	cmp	r1, #0
	beq	core_init_fail
	cmp	r2, #0
	beq	core_init_fail
	/* Disable the UART before initialization */
	ldr	r3, [r0, #UARTCR]
	bic	r3, r3, #PL011_UARTCR_UARTEN
	str	r3, [r0, #UARTCR]
	/* Program the baudrate */
	/* Divisor =  (Uart clock * 4) / baudrate */
	lsl	r1, r1, #2
	udiv	r2, r1, r2
	/* IBRD = Divisor >> 6 */
	lsr	r1, r2, #6
	/* Write the IBRD */
	str	r1, [r0, #UARTIBRD]
	/* FBRD = Divisor & 0x3F */
	and	r1, r2, #0x3f
	/* Write the FBRD */
	str	r1, [r0, #UARTFBRD]
	mov	r1, #PL011_LINE_CONTROL
	str	r1, [r0, #UARTLCR_H]
	/* Clear any pending errors */
	mov	r1, #0
	str	r1, [r0, #UARTECR]
	/* Enable tx, rx, and uart overall */
	ldr	r1, =(PL011_UARTCR_RXE | PL011_UARTCR_TXE | PL011_UARTCR_UARTEN)
	str	r1, [r0, #UARTCR]
	mov	r0, #1
	bx	lr
core_init_fail:
	mov	r0, #0
	bx	lr
endfunc console_core_init

	/* ---------------------------------------------
	 * int console_putc(int c)
	 * Function to output a character over the
	 * console. It returns the character printed on
	 * success or an error code.
	 * In : r0 - Character to be printed
	 * Out : r0 - Input character or error code.
	 * Clobber list : r1, r2
	 * ---------------------------------------------
	 */
func console_putc
	ldr	r1, =console_base
	ldr	r1, [r1]
	b	console_core_putc
endfunc console_putc

	/* --------------------------------------------------------
	 * int console_core_putc(int c, uintptr_t base_addr)
	 * Function to output a character over the console. It
	 * returns the character printed on success or an error
	 * code.
	 * In : r0 - Character to be printed
	 *      r1 - Console base address
	 * Out : r0 - Input character or error code.
	 * Clobber list : r2
	 * --------------------------------------------------------
	 */
func console_core_putc
	/* Check the input parameter */
	cmp	r1, #0
	beq	putc_error
	/* Prepend '\r' to '\n' */
	cmp	r0, #0xA
	bne	2f
1:
	/* Check if the transmit FIFO is full */
	ldr	r2, [r1, #UARTFR]
	tst	r2, #PL011_UARTFR_TXFF
	bne	1b
	mov	r2, #0xD
	str	r2, [r1, #UARTDR]
2:
	/* Check if the transmit FIFO is full */
	ldr	r2, [r1, #UARTFR]
	tst	r2, #PL011_UARTFR_TXFF
	bne	2b

	/* Only write 8 bits */
	and	r0, r0, #0xFF
	str	r0, [r1, #UARTDR]
	bx	lr
putc_error:
	mov	r0, #ERROR_NO_VALID_CONSOLE
	bx	lr
endfunc console_core_putc

	/* ---------------------------------------------
	 * int console_getc(void)
	 * Function to get a character from the console.
	 * It returns the character grabbed on success
	 * or an error code on error. This function is
	 * blocking, it waits until there is an
	 * available character to return.
	 * Out : r0 - Return character or error code.
	 * Clobber list : r0 - r3
	 * ---------------------------------------------
	 */
func console_getc
	ldr	r2, =console_base
	ldr	r2, [r2]
	mov	r3, lr

	/* Loop until it returns a character or an error. */
1:	mov	r0, r2
	bl	console_core_getc
	cmp	r0, #ERROR_NO_PENDING_CHAR
	beq	1b

	bx	r3
endfunc console_getc

	/* ---------------------------------------------
	 * int console_try_getc(void)
	 * Function to get a character from the console.
	 * It returns the character grabbed on success
	 * or an error code on error. This function is
	 * non-blocking, it returns immediately.
	 * Out : r0 - Return character or error code.
	 * Clobber list : r0, r1
	 * ---------------------------------------------
	 */
func console_try_getc
	ldr	r0, =console_base
	ldr	r0, [r0]
	b	console_core_getc
endfunc console_try_getc

	/* ---------------------------------------------
	 * int console_core_getc(uintptr_t base_addr)
	 * Function to get a character from the console.
	 * It returns the character grabbed on success
	 * or an error code.
	 * In : r0 - Console base address
	 * Out : r0 - Return character or error code.
	 * Clobber list : r0, r1
	 * ---------------------------------------------
	 */
func console_core_getc
	cmp	r0, #0
	beq	getc_error

	/* Check if the receive FIFO is empty */
	ldr	r1, [r0, #UARTFR]
	tst	r1, #PL011_UARTFR_RXFE
	bne	getc_empty

	/* Read a character from the FIFO */
	ldr	r1, [r0, #UARTDR]
	/* Mask out error flags */
	and	r0, r1, #0xFF
	bx	lr

getc_empty:
	mov	r0, #ERROR_NO_PENDING_CHAR
	bx	lr
getc_error:
	mov	r0, #ERROR_NO_VALID_CONSOLE
	bx	lr
endfunc console_core_getc

	/* ---------------------------------------------
	 * int console_flush(void)
	 * Function to force a write of all buffered
	 * data that hasn't been output. It returns 0
	 * upon successful completion, otherwise it
	 * returns an error code.
	 * Out: r0 - Error code or 0.
	 * Clobber list : r0, r1
	 * ---------------------------------------------
	 */
func console_flush
	ldr	r0, =console_base
	ldr	r0, [r0]
	b	console_core_flush
endfunc console_flush

	/* ---------------------------------------------
	 * int console_core_flush(uintptr_t base_addr)
	 * Function to force a write of all buffered
	 * data that hasn't been output.
	 * In : r0 - Console base address
	 * Out : r0 - Error code or 0.
	 * Clobber list : r0, r1
	 * ---------------------------------------------
	 */
func console_core_flush
	cmp	r0, #0
	beq	flush_error

1:
	/* Loop while the transmit FIFO is busy */
	ldr	r1, [r0, #UARTFR]
	tst	r1, #PL011_UARTFR_BUSY
	bne	1b

	mov	r0, #0
	bx	lr
flush_error:
	mov	r0, #ERROR_NO_VALID_CONSOLE
	bx	lr
endfunc console_core_flush